#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <fstream>
#include <iterator>
#include <random>
#include <assert.h>
using namespace std;

const string file = "cuplaj";

const string infile = file + ".in";
const string outfile = file + ".out";

const int INF = 0x3f3f3f3f; 

//#define ONLINE_JUDGE

int N, M;
vector<int> Lpair;
vector<int> Rpair;
vector<vector<int> > G;

vector<bool> viz;


bool canPair(int x)
{
    if(viz[x] == true)
        return false;

    viz[x] = true;

    for(vector<int>::iterator itr = G[x].begin();
            itr != G[x].end();
            itr++)
    {
        if(Rpair[*itr ] == -1 || canPair(Rpair[*itr]))
        {
            Lpair[x] = *itr;
            Rpair[*itr] = x;
            return true;
        }
    }

    return false;
}

int main()
{
#ifdef ONLINE_JUDGE
	ostream &fout = cout;
	istream &fin = cin;
#else
	fstream fin(infile.c_str(), ios::in);
	fstream fout(outfile.c_str(), ios::out);
#endif	

    int E;
    fin >> N >> M >> E;
    G.resize(N + 1);
    Lpair.resize(N + 1, -1);
    Rpair.resize(M + 1, -1);
    viz.resize(N + 1, false);
    for(int i = 0; i < E; i++)
    {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
    }

    bool improv = true;
    int Sol = 0;
    while(improv)
    {
        fill(viz.begin(), viz.end(), false);
        improv = false;
        for(int i = 1; i <= N; i++)
        {
            if(Lpair[i] == -1 && canPair(i))
            {
                improv = true;
                Sol++;
            }
        }
    }

    fout << Sol << "\n";
    for(int i = 1; i <= N; i++)
    {
        if(Lpair[i] != -1)
        {
            fout << i << " " << Lpair[i] << "\n";
        }
    }

#ifdef ONLINE_JUDGE
#else
    fout.close();
	fin.close();
#endif
}